The present invention relates to walk-behind mowers with mechanisms for adjusting the deck height and drive speed. In particular, the present invention relates to walk-behind mowers with an independent hydrostatic transmission for each of two rear wheels carrying a deck containing one or more cutting blades, where the height of the deck is adjustable.
Adjustment of the deck height determines the amount of vegetation that is cut. For example, at golf courses, the fairways are mowed at a much shorter deck height than are the rough or out of bounds. It is also advantageous to be able to adjust the deck height setting on mowers used by homeowners as grass height preferences tend to vary between owners and additionally it is often necessary to adjust the deck height depending on the terrain that is to be mowed. Sloped and uneven ground often requires the use of a higher deck height than level ground. Adjustments of the deck height for walk behind mowers is time consuming. The adjustment requires the engine of the mower to be shut off and, in some cases, manual adjustments of each corner of the deck must be made.
With respect to the rate of travel of the mower, the speed is a function of a transmission control that varies the rate at which fluid is pumped by the hydrostatic transmission. Hydrostatic transmissions are known in the art and include fluid pumps driven by the mower engine, and a hydraulic motor for transforming the hydraulic power into torque and rotation speed for operating the wheels. Once the transmission control is adjusted to a desired rate of travel, the operator activates one or more levers on the mower handle to engage the hydrostatic transmission. The operator then commences walking behind the mower at the operating speed selected. At the end of a cutting pass, the mower is steered to a new cutting direction by operating only one of the hydrostatic drives of the rear wheels. If the mower is to be driven at a higher rate of speed, such as is desirable when moving the mower from one area to a more distant area, the mower is stopped by releasing both transmission engagement levers, readjusting the transmission rate control, and then reengaging the transmission engagement levers.
As time and efficiency are important factors in mowing, improvements in deck height adjustment and drive speed adjustment are needed in walk behind mowers.